Lab Manual Computer Aided Engineering Graphics ECE 151-251

Computer Aided Engineering Graphics (ECE-151/251)

Indus Institute of Technology and Management Bilhaur, Kanpur-209202 Mechanical Engineering Department Semester I & II

Lab manual for Computer Aided Engineering Graphics (ECE-151/251)

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Index

Sr No.

Title

Page Number

1

Syllabus

2

2

Introduction to Computer Aided Sketching

3-8

3

AutoCAD & Commands

9-15

4

Projections

16

5

Exercises

17-18

6

Important questions

19-20

7

Do’s and Don’ts

21

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Computer Aided Engineering Graphics (ECE-151/251) Computer Aided Engineering Graphics (ECE-151/251) SYLLABUS ECE-151/251: COMPUTER AIDED ENGINEERING GRAPHICS LTP

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Unit-I 1. Introduction to Computer Aided Sketching Introduction, Drawing Instruments and their uses, BIS conventions, lettering Dimensioning and free hand practicing. Computer screen, layout of the software, standard tool bar/menus and description of most commonly used tool bars, navigational tools. Coordinate system and reference planes. Definitions of HP, VP, RPP & LPP. Creation of 2D/3D environment. Selection of drawing size and scale. Commands and creation of Lines, Co-ordinate points, axes, poly-lines, square, rectangle, polygons, splines, circles, llipse, text, move, copy, off-set, mirror, rotate, trim, extend, break, chamfer, fillet, curves, constraints viz. tangency, parallelism, inclination and perpendicularity. Dimensioning, line convention, material conventions and lettering. 2-Sheet 2. Orthographic Projections Introduction, Definitions- Planes of projection, reference line and conventions employed, Projections of points in all the four quadrants, Projections of straight lines (located in First quadrant/first angle only), True and apparent lengths, True and apparent inclinations to reference planes (No application problems). 2-Sheet 3. Orthographic Projections of PlaneSurfaces (First Angle Projection Only) Introduction, Definitions-projections of plane surfaces-triangle, square rectangle, rhombus, pentagon, hexagon and circle, planes in different positions by change of position method only (No problems on punched plates and composite plates.) 1-Sheet 4. Projections of Solids (First Angle Projection Only) Introduction, Definitions- Projections of right regular- tetrahedron, hexahedron (cube), prisms, pyramids, cylinders and cones in different positions. (No problems on octahedrons and combination solid) 2-Sheet 5. Sections and Development of Lateral Surfaces of Solids Introduction, Section planes, Sections, section views, Sectional views, apparent shapes and True shapes of Sections of right regular prisms, pyramids, cylinders and cones resting with base on HP. (No problems on section of solids) 1-Sheet Development of lateral surface of above solids, their frustums and truncations. (No problems on lateral surfaces of trays, Tetrahedrons spheres and transition pieces). 6. Isometric Projection (Using Isometric Scale Only) Introduction, Isometric scale, Isometric Projection of simple plane figures, Isometric Projection of tetrahedron, hexahedron (cube), right regular prisms, pyramids, cylinders, cones, spheres, cut spheres and combination of solids (Maximum of three Solids). 1-Sheet Note: At least 3 drawing assignments must be on AUTOCAD. Text Book 1. Engineering Drawing - N.D. Bhatt & V.M. Panchal, 48th edition, 2005 Charotar Publishing House, Gujarat. 2. A Primer on Computer Aided Engineering Drawing-2006, Published by VTU, Belgaum. Reference Book 1. Computer Aided Engineering Drawing - S. Trymbaka Murthy, - I.K. International Publishing House Pvt. Ltd., New Delhi, 3rd revised edition-2006. 2. Engineering Graphics - K.R. Gopalakrishna, 2005, Subash Publishers, Bangalore. 3. Fundamentals of Engineering Drawing with an Introduction to Interactive Computer Graphics for Design and Production - Luzadder Warren J., duff John M., Eastern Economy Edition, 2005 - Prentice-Hall of India Pvt. Ltd., New Delhi.

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INTRODUCTION

The purpose of (Computer Aided Engineering Graphics) CAEG is to give you the basics of engineering sketching and drawing. “Sketching” and “Drawing”: Sketching generally means freehand drawing; without using any drawing

instruments. i.e.: Sketch the face of human being. Drawing is usually means drawing made by using drawing instruments. Example: Draw the chair which is used to sit. Engineering Drawing is a document that communicates a precise description of a part. They are legal documents, so they must be formal and precise. They are drawn using different tools and instruments from compasses to drafters to bring precision to the drawings. Example: Draw the chair with dimensions so that they can be manufactured. Computer Aided Engineering Drawing is a file that communicates a precise description of a part with all details. Wherein they can be easily edited as per requirements of individual (customized). They are drawn using Computer and CAD software as a tool. “Engineers can convert the ideas into drawing and then in reality.” Drawings communicates through the use of graphical symbols such as points, lines, planes and pictures and gives the detailed description about any component in a pictorial form. Technical Graphics, also called as Engineering Drawing is a graphics language. It cannot be spoken or read out like many languages having phonetics and script. The knowledge of the language of graphics communications will influence the way of thinking. Normally, human thoughts are interlinked with the language they know. The engineering problems can be more clearly visualized through Technical Graphics or Engineering Drawing and can help to find solutions with greater ease. A designer has to imagine about many features of an object that cannot be communicated by verbal/written description. The designs are thought in the mind of designer in terms of „visual images‟. They can be reviewed and modified before they are finalized. The designer translates the mental picture into a drawing or model that will produce a similar picture in the mind of everyone who sees the drawing.

OBJECTIVES IN DRAWING Accuracy: The drawings are not useful to the maximum extent if they are not accurate. Speed: “Convert Time into Money” in industry. There is no place for the slow technician, or engineer. Speed is not attained in a hurry; it should be with intelligent and continuous work. It comes with practice. Legibility: Drawing is a means of communication to others, and that it should be clear and legible to serve its purpose. Care should be taken especially in dimensioning and lettering. Neatness: If a drawing is to be acceptable it should be clean and neat because even small dust particle can act as smallest entity as point.

DRAWING INSTRUMENTS and Uses The accuracy and speed of the Engineering Drawing is aided by tools. The conventional tools used to make engineering drawing have evolved over years to develop geometry. Conventional tools are devices used in making engineering drawings. It includes drawing straight lines, inclined lines, making arcs and circles, to increase speed with which drawings are made. The tools and accessories typically used are: (a) Wood and Mechanical Pencils (2H, H, HB, B, 2B, etc.) (b) T-square or Minidrafter, 45° and 30°/60° set squares (triangles) (c) Compass and dividers (d) Protractor (e) Eraser

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Computer Aided Engineering Graphics (ECE-151/251) (f) Scales set (metric) (g) Irregular curve (French curves) (h) Drawing sheets (A1/A2/A3/A4 size) (i) Drawing Clips (j) Drawing Board (k) Drafter, etc.

COMPUTER AIDED DRAWING TOOLS Conventional tools can be useful for sketching and rough layout. The use of computers in every phase of engineering, design, drawing, analysis is well known. The integration of computers into the manufacturing industry from design to marketing, is changing the methods used in the technical education and training of technicians, designers and engineers. A computer system consists of hardware and software. The various pieces of physical equipment that comprises a computer system are known as hardware. The programs, instructions that permit computer system to operate ( and not visible )are classified as software. Computer software is categorized as either application programs or operating system (OS) programs. Operating system programs are set of instructions that control the operation of computer and peripheral devices. This type of program may also provide support for activities and programs such as input/output (I/O) control, editing, storage, assigning drives for I/O, in addition to providing support for standard system commands and networking. Names of some typically used hardware are: Central Processing Unit Hard Disk Display Devices Input Devices (a) Tablet or Digitizer (b) Mouse (c) Scanners (d) Keyboard Output Devices (a) Printers and plotters Software A computer program that provides specific instructions to enable a computer to do a certain task is called software. When CADD software is purchased from a manufacturer, it is known as application program or application software. This specialized software provides service for a specific endeavor such as mechanical drawing, piping layout, solid modeling, structural, and architectural drawing. CAD Software The computer programs designed for specific tasks in response to user‟s requirements are called application software. It is time consuming, tedious, and expensive to develop application programs and 4

Computer Aided Engineering Graphics (ECE-151/251) hence it is considered advantageous to buy existing software. Some of the CAD software used for drafting and design are: Software Developer, THINK3, Auto CAD, Pro/Engineer, CATIA, Unigraphics, Solidworks.

Layout of drawing sheet Layout of the drawing refers to the position of different parts/ areas of the drawing.

Title Block The title block should be within the drawing space located at the bottom right hand corner. The direction of viewing of the title block should correspond in general with that of the drawing. Title block should preferably consist of one or more adjoining rectangles. Title blocks used are shown in Figure 1.4. These may be sub-divided into boxes for the insertion of specific information such as: (i) Name of the firm (ii) Title of the drawing (iii) Drawing number (iv) Scale (v) Projection symbol (first angle or third angle) (vi) Drawing number (vii) Initials of staff designed, drawn, and approved by.

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Computer Aided Engineering Graphics (ECE-151/251) BIS CONVENTIONS FOR LETTERING AND DIMENSIONS Standards like Bureau of Indian Standards (BIS), International Standards Organization (ISO), etc., are used in engineering drawing practice. SP46:2003 gives the consolidated list of BIS and ISO codes for engineering drawing practice.

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Computer Aided Engineering Graphics (ECE-151/251) MATERIAL CONVENTIONS The conventions followed to represent some of the materials on the drawing are as:

LETTERING AND DIMENSIONING WITH AutoCAD Lettering is called text when using a CAD system. The TEXT or FONT command is one of that is found in a section of the menu labeled text. The first decision regarding the text is to determine its height, width, and slant angle. Most CAD systems maintain default text size that is used if the operator chooses not to change it. Location can be identified using a pointing input device. After deciding the location, text can be keyed in. Another method is type the text and it appears on the screen with the crosshairs at the point of location previously specified. Then the text can be dragged to the desired location, and placed in the position by pressing a button on the keyboard or mouse. Dimensioning is the process of mentioning of distance and called as distance, angular dimension, and smart dimension when using a CAD system. The command is executed by selecting the icon and click on the geometry to get the dimensions. Even the arrow head/slash/dot is mentioned as per requirement and is taken care using CAD system very systematically as per standards. Engineering Drawings are prepared to show the shape and size of the product/object to be manufactured or constructed. Shape is described by projection and size is described by the dimensions. All objects are in three dimensions (3D) whereas the picture plane or projection planes are in two dimensions (2D). The 3D objects are represented in a 2D plane by means of projections. Printing the drawing File—plot-- Set the printer name (ask the staff)—set paper size (A4) Set plot area as Limits Or extents Tick the center the plot Tick the Fit to paper Preview OK

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AUTO CAD AND COMMANDS The complete working area along with all other facilities is shown below after launching of AutoCAD.

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Computer Aided Engineering Graphics (ECE-151/251) PROJECTIONS Projection is a process of making OR causing an image by rays of light taken in a particular direction from an object to a picture plane. The imaginary ray of light between the object and the projection plane is called line of sight or projector. The projection methods are categorized as: First Angle Projection An arrangement of vertical, horizontal, and profile planes and quadrants used to draw first angle projections is shown below. Front view is projected onto the vertical plane, top view onto the horizontal plane, and side view onto the profile plane. An object placed in the first quadrant. The vertical plane is behind the object, horizontal plane below the object, and profile plane to right of the object. The views with the corresponding planes are shown in figure. The top view is seen below the elevation and left side view is seen on the right of front view. This is the arrangement of views in the first angle projection.

Multi-view Projection It consists of a set of two or more orthographic views of an object taken from different directions which are mutually perpendicular. These views are arranged relative to each other in a particular way. Each of these views shows the shape of the object for a particular viewing direction. Multiple views collectively describe the object completely and exactly. Hence multi-view projections are used in engineering to describe the true shape of any object.

Orthographic Projection In orthographic projection, the projectors are parallel and perpendicular to the plane of projection. Orthographic projections on mutually perpendicular projection planes will fully describe the object in its shape and size. Hence, all design and manufacturing drawings are made with orthographic projections.

Projection in Third Angle An object placed in the third quadrant. The vertical plane is in front of the object, horizontal plane above the object and profile plane to the left of the object. The views with corresponding planes are shown in figure. Top view is above the front view and left side view is to the left of the front view. This is the arrangement of the views in third angle projection.

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EXERCISES Draw the following drawings using AutoCAD. 1. EXPERIMENT NO. 1 Title: To make a drawing on AutoCAD.

given

Introduction: The drawings are the media of communication for the engineers and autoCAD facilitates the easy and fast development, editing and communication of the drawings. ITEMS REQUIRED: AutoCAD Software and the given drawing STANDARD PROCEDURE: a) b) c) d) e) f) g) h) i) j)

Launch AutoCAD Set the drawing limits. Set the units. Put ON the grid Draw the lines as per the dimensions using the line command. Draw the circle using the circle command. Insert the dimensions using the dimensioning. Insert the text using text command. Insert the table using the table command. Write the Name, class & other details as per the drawing, in the table.

RESULTS & FINDINGS: Take the print out of your drawing. CONCLUSIONS: Compare your drawing with the given drawing to evaluate. Correct if required. SHORT QUESTIONS & ANSWERS: (Provided on page no 21)

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Computer Aided Engineering Graphics (ECE-151/251) 2.

3.

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Computer Aided Engineering Graphics (ECE-151/251) 4.

IMPORTANT QUESTIONS 1. BIS recommends ……………………..method of projection in India. Ans-First angle 2. Dimensions should be placed ……….. the view of drawing. Ans- outside 3. Dimension lines are drawn by ……… lines. Ans- thin 4. Hidden lines are shown by ………..lines. Ans-dashed 5. French curve is used for drawing the curves which cannot be made by compass. 6. The title block is located on the right hand bottom of the drawing. 7. What is the symbol for the first angle projection? 8. What is the symbol for the Third angle projection? 9. In orthographic projection the projectors are normal to the plane of projection. 10. The letter ‘L’ is written, using vertical single stroke letter as ‘L’ and sloped letter is written as ‘L’. 11. How do you define the cube? Ans- All the six faces and eight edges are equal. 12. What is the symbol for LINE command in autoCAD? 13. What is the symbol for CIRCLE command in autoCAD? 14. What is the symbol for TEXT command in autoCAD? 19

Computer Aided Engineering Graphics (ECE-151/251) 15. What is the symbol for POINT command in autoCAD? 16. What are the two methods of placing the dimensions? 17. What are the methods of projection based on the angle of projections? 18. Write the letter ‘A’ using gothic letters. Ans- A 19. In first angle method of projection the object is placed in the first quadrant. 20. In third angle method of projection the object is placed in the third quadrant. 21. What is the symbol for RECTANGLE command in autoCAD?

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Computer Aided Engineering Graphics (ECE-151/251) Lab Safety – Do’s and Don'ts

Computer Aided Engineering Graphics LAB DO’S

LAB DON’TS

Know the location of all safety and emergency equipment used in the lab

NEVER experiment on your own.

Keep you work area clean and clutter free

Do not eat or drink in the lab room at any time.

The computers of the LAB are responsibility of the LAB Do not chew gum or eat users. Keep your computer candy during lab exercises. clean and take a good care of them. LAB is for educational purpose. Use it for educational purpose only.

Don't interchange any part of one computer with another.

Switch OFF the computers of the LAB while leaving the LAB. In case of any hardware related problem, ask LAB in charge for solution. If you are the last one leaving the LAB, make sure that the stuff in charge of the LAB is informed to close the LAB.

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Lab Manual Computer Aided Engineering Graphics ECE 151-251

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